Polymers of halogen containing n-alkenyl carbamates

ABSTRACT

Polymers of halogenated carbyl-N-alkenyl carbamates represented by the formula: WHEREIN A is halogenated carbyl such as haloalkyl or haloaryl, Y is alkenyl such as vinyl or allyl and a is 1 or 2. Polymers of such carbamates and other ethylenically unsaturated monomers are generally found to be self-extinguishing.

United States Patent Dolinski et al.

[4 1 May 30, 1972 [54] POLYMERS OF HALOGEN CONTAINING N-ALKENYLCARBAMATES [72] Inventors: Richard .I. Dollmkl; Robert M. Nowlk, both ofMidland; George A. Burk, Bay

City, all of Mich.

[731 Assignee: The Dow Chemical Company, Midland,

Mich.

[221 Filed: June 22, 1970 [21] Appl.No.: 48,485

2,863,488 l2/ 1958 Short ct al. ..260/77.5

Primary Examiner-Donald E. Czaja Assistant Examiner-M. 1. WelshAttorney-Griswold & Burdick, R. G. Waterman, L. 1. Dankert and M. S.Jenkins 57 ABSTRACT Polymers of halogenated carbyl-N-alkenyl carbamatesrepresented by the formula:

wherein A is halogenated carbyl such as haloalkyl or haloaryl, Y isalkenyl such as vinyl or allyl and a is l or 2. Polymers of suchcarbamatcs and other ethylenically unsaturated monomers are generallyfound to be self-extinguishmg.

14 Clalrm, No

POLYMERS OF HALOGEN CONTAINING N-ALKENYL CARBAMA'I'ES BACKGROUND OF THEINVENTION This invention relates to polymers of N-alkenyl carbamatescontaining halogen including fire resistant copolymers of suchcarbamates and other ethylenically unsaturated monomers.

Fire-resistant polymers which are useful in protective coatings andfabricated articles would be most desirable. Of particular interestwould be copolymers containing large proportions of common monomers suchas styrene and substituted styrenes which exhibit self-extinguishingcharacteristics yet which possess the physical characteristics ofstyrene-type polymers.

Heretofore it has been a common practice to render styrene polymers fireretardant by blending non-combustible additives, e.g., halogencontaining additives, therewith. However, such additives are oftennon-permanent for the styrene polymers as they are readily extractedduring most washing or similar such procedures carried out duringfabrication.

These halogen-containing additives are thought to provide flameproofingproperties by decomposing at elevated temperatures in the flame toproduce hydrogen halide which extinguishes the flame. Unfortunately,many of such additives decompose and release hydrogen halide attemperatures substantially below the flame temperature of burningpolymer. Since many plastic articles are produced by fabricating thepolymer at an elevated temperature, the flame retarding additivepreviously incorporated into the polymer tends to undergo at leastpartial decomposition. As a result of this partial decomposition,hydrogen halide is released causing corrosion of the fabricationequipment. Corrosion inhibitors have been added to the polymer to combatthis problem; however they' have not been completely effective in thisregard and their presence may adversely affect other properties of thepolymer. In addition to the corrosion problem the breakdown of thehalogenated compound usually produces discoloration of the finishedplastic which is particularly undesirable in the case of transparentplastics such as polystyrene. A further problem is that of instabilityto light. Self-extinguishing plastic articles which are exposed tosunlight may become discolored as a result of the photochemical effectsof the actinic rays on the halogenated compounds.

Therefore, it would be highly desirable to provide polymers which havepermanent flame retarding characteristics and which do not undergodecomposition at temperatures employed to fabricate such polymers.

SUMMARY OF THE INVENTION general formula:

F E l A- NH-Y wherein A is haloalkyl, haloalkenyl, haloaryl,haloalkylene or haloarylene; Y is aliphatic group having a terminaldouble bond and a is one or two. Such polymers are found to be generallyfire retardant and to be efi'ective materials for protective coating andfabrication. In particularly important embodiments, this inventionconcerns copolymers of conventional ethylenically unsaturated monomerssuch as styrene or substituted styrenes and the above describedcarbamates. Such copolymers are generally self-extinguishing and usuallypossess physical properties such as strength and processabilitygenerally comparable with or better than homopolymers of the particularethylenically unsaturated monomer. These copolymers are particularlyuseful in the fabrication of shaped articles and in other moldingapplications. Examples of uses DETAILED DESCRIPTION OF THE PREFERREDEMBODIMENTS As more particularly defined, the polymerizable carbamatesemployed in the present invention are halogenated carbyl-N- alkenylcarbamates as represented by the formula:

A[ O ENE-Y1 wherein a is l or 2 and A and Y are as defined hereinbeforeand hereinafier.

Halogenated carbyl which corresponds to A is suitably haloalkyl havingfrom two to eight carbon atoms, halo-alkenyl having from two to eightcarbon atoms, haloaryl having from six to 16 carbon atoms, haloalkylenehaving from two to eight carbon atoms, or haloarylene having from six tol6 carbon atoms. Chlorine, bromine and iodine are suitable halogens,with bromine being preferred. To maximize the self-extinguishingcharacteristics of the resultant polymer, it is preferable thathalogenated carbyl contain sufficient halogen atoms to provide a ratioof halogen atoms: carbon atoms in the carbamate of at least 1:4,especially 1:3 to 1:2. Advantageously halogenated carbyl is a mono ordivalent radical represented by one of the following formulas:

wherein R is halogen or haloalkyl; R R, and R, are individuallyhydrogen, alkyl having from one to eight carbon atoms, alkenyl havingfrom two to eight carbon atoms, aryl having from six to 16 carbon atoms,haloalkyl having from one to eight carbon atoms, haloalkenyl having fromtwo to eight carbon atoms, or haloaryl having from six to 16 carbonatoms provided at least one of R and R contains halogen; c is zero or awhole number from 1 to 6; f is a whole number from 2 to 6, and g is awhole number from 1 to 5. For the purposes of this invention the terms"haloalkyl, haloalkenyl," haloaryl," haloalkylene" and haloarylene"include both monohaloradicals and polyhaloradicals with polyhaloradicalsgenerally having from 2 to 10 halogen atoms not necessarily of the samehalogen.

Aliphatic groups having terminal double bonds which correspond to Y aresuitably vinyl, allyl, isopropenyl, acryloyl, methacryloyl, ethacryloyland other alkenyl groups having a terminal double bond. Preferably Y isan alkenyl group represented by the formula:

wherein R, and R, are individually hydrogen or alkyl having from one tosix carbon atoms and b is zero or a whole number from 1 to 6.

Polymerizable carbamates employed in this invention are readily preparedby reacting unsaturated isocyanates of the formula Y-NCO with alcoholsof the formula: A(OH), wherein Y and A are as hereinbefore set forth.

Suitable isocyanates containing polymerizable vinyl group include vinylisocyanate, allyl isocyanate, isopropenyl isocyanate, acryloyl,methacryloyl, and ethacryloyl isocyanates. Vinyl, isopropenyl and allylisocyanates are readily prepared by the method described by D. Heinertin US. Pat. No. 3,470,228. Acryloyl, methacryloyl and ethacryloylisoinclude auto parts such as dash boards and kick panels,insulacyanates can be prepared by the method described by Lieser andKemmer in Chem. Berg. 84 4( 1951 During preparation of the alkenylisocyanate, it is desirable to employ a polymerization inhibitor in thereaction mixture. Exemplary of such inhibitors are hydroquinone,quinone, t-butyl-catechol and the like which are beneficially used inamounts of 0.05 to 0.2 weight percent based on the reaction mixture.

Alcohols corresponding to the formula A -(OH), are readily available orcan be easily prepared by conventional organic synthesis.Illustratively, however, tri-bromoneopentyl alcohol can be prepared byreacting pentaerythritol with hydrogen bromide in glacial acetic acid toproduce a tribromopentaerythrityl acetate. The desired alcohol is thenproduced by transesterification of this product with methanol. Examplesof suitable alcohols include tribromoneopentyl alcohol,2,3-dibromopropyl alcohol, 2,3,3-tribromoallyl a1- cohol,2,3,4,5,6-pentabromophenol, 2-bromoethyl alcohol, trichloroneopentylalcohol, 2,2-bis(chloromethyl l ,3- propanediol,2,2-bis(bromomethyl)-l,3-propanediol, 2,2- bis(chloromethyl)butanol,2,2-bis(bromomethyl)hexanol and corresponding alkanols and1,3-propanediols having both chloromethyl and bromomethyl substituents.

in the preparation of the carbamate, the alkenyl isocyanate isadvantageously added to the halogen-containing alcohol in an inerthalohydrocarbon solvents such as chloroform or carbon tetrachloride andpreferably in the presence of an organometallic catalyst such as dibutyltin diacetate. Other materials known to catalyze the reaction ofalcohols with isocyanates are also suitable. The order of addition isnot particularly critical. However, the reaction is exothermic,therefore portionwise addition of one component to the other isgenerally desired in order to control the reaction temperatures.Reaction temperature is also not critical as it is found that thedesired reaction proceeds at temperatures in the range from to 150 C.Preferably, however, the reaction is carried out at ambient or nearambient temperatures, e.g., from 25 to 80 C. Since isocyanates reactreadily with water, the reaction is preferably conducted underessentially anhydrous conditions, i.e., not more than 1,000 ppm total ofwater present in the reaction mixture. This problem can be furtheralleviated by employing excess isocyanates which will react with anyaqueous impurity. In addition, it is preferable to carry out thereaction of isocyanate with alcohol under substantially oxygen-freeconditions. Molar ratio of isocyanate to alcohol may vary considerably,e.g., from 1.5:1 to 1:1. However, since the reaction is quantitative at121, this ratio or ratios near 1:1 are preferred. When this reaction iscarried out in a solvent, usually an inert halohydrocarbon mentionedbefore or inert hydrocarbon such as toluene or benzene is employed insufficient amounts such that the resulting reaction mixture isstirrable. Typically one or two liters of solvent is sufficient if up to1 gram mole of each reactant is employed.

The carbamates as described hereinbefore are readily homopolymerized inthe presence of a free-radical generating catalyst such asazobisisobutyronitrile. The resultant homopolymers are similar topolystyrene and can be generally characterized and are useful in moldingand other polymer shaping applications.

In addition these carbamates are readily copolymerized with othermonoethylenically unsaturated comonomers under conditions similar tothose employed in homopolymerization thereof to form polymers havingsignificantly better fire resistance and equivalent or better physicalcharacteristics than homopolymers of the particular ethylenicallyunsaturated monomer. Typical of monoethylenically unsaturated comonomerswhich can be copolymerized with the aforementioned carbamates arestyrene and substituted styrenes such as a-methylstyrene,ar-methylstyrene, ar-t-butylstyrene, archloro-, ar-bromo-, ar-dibromo-,ar-di-chloroand artrifluoro-styrenes and the like; acrylates andmethacrylates such as ethyl acrylate, ar-butyl acrylate, isobutylacrylate; methyl methacrylate and the like, acrylonitrile,methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chlorideand the like. The amounts of etl' ylenically unsaturated comonomersemployed with the carbamate will vary depending on the particularapplication desired. Generally, however, it is desirable to employ suchcomonomers in amounts ranging from 50 to 98 weight percent based on thecopolymer. To realize significant improvement in fire resistance, thecarbamate should be employed in amounts of at least 2 weight percentbased on the copolymer, preferably at least 3 weight percent. It isunderstood that mixtures of two or more of the comonomers and/ormixtures of two or more carbamates may be employed in preparation ofsuch copolymers.

If a substantially cross-linked polymer or copolymer is desired, apolyethylenically unsaturated polymerizable monomer can be added to themonomer mixture prior to polymerization. Polyethylenically unsaturatedmonomers suitable as crosslinking agents, usually in amounts up to 5weight percent based on monomer mixture, include divinylbenzene,trivinylbenzene, divinylnaphthalene, glycoldiacrylates anddimethacrylates, divinoxyethane and trivinoxypropane and the like.

The aforementioned carbamates, alone or in admixture with otherethylenically unsaturated comonomers as set forth hereinbefore, arereadily polymerized at ambient or near ambient temperatures andpressures with the aid of a free-radical generating catalyst.Polymerization is most suitably conducted, however, at temperatures inthe range from about to about 90 C. Free radical generating catalystssuitably employed include organic or inorganic peroxides such as diethylperoxides, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide,hydrogen peroxide, and the like; a salt of a peracid such as ammoniumpersulfate, sodium perborate, potassium percarbonate and the like; oractive organic azo catalysts such as a, a-azobis(a,'y-di-methyl-valeronitrile, azobisisobutyronitrile and the like.

The following examples are given to illustrate the invention and shouldnot be construed as limiting its scope. Unless otherwise indicated, allparts and percentages are by weigh t.

EXAMPLE 1 Found Calculated C 25.0 24.3 H 3.3 3.55 N 3.7 3.55 Br 60.460.8

A l7-g. portion (0.043 mole) of the recovered tribromoneopentyl-N-vinylcarbamate and 153 g. (1.47 moles) of styrene are added to a glass bombwith 0.85 g (0.5 percent) of azobisisobutyronitrile. The bomb is purgedwith nitrogen for 5 minutes, sealed and immersed in a constanttemperature water bath at 60 C for 17 hours. The bomb is then opened andthe contents are dissolved in benzene. The polymer is reprecipitatedtwice from methanol and dried in a vacuum oven at C for 24 hours.Results of elemental analysis of the polymer are as follows:

Calculated for 10% Found, Carbamate,

C 85.5 85.4 H 7.3 7.2 N 0.2 0.3

Copolymer structure is confirmed by infrared spectral analysis. Thiscopolymer is compression molded at -195 C into test bars (6 x A X isinch) which are subjected to the standard burn tests: UnderwritersSubject No. 94 test (UL-94) and ASTM D-635. The bars pass both testswith regard to selfextinguishing characteristics (Class II). Acomposition passes the Underwriters test, i.e., is Class IIself-extinguishing if less than 25 seconds are required for the flame toextinguish when a burning specimen of the melt is withdrawn from aflame.

Other copolymers of tribromoneopentyl-N-vinyl carbamate and styrene areprepared in manner similar to preceding procedures except that theproportions of the monomers are varied sufficiently to yield copolymercontaining 1.5 percent, 2.1 percent, 3 percent and 6.8 percent of thecarbamate. These copolymers are molded into test bars and subjected tothe rigors of UL-94 and ASTM D635. The copolymers containing 3 percentor more of the carbamate pass both tests whereas those containing 1.5percent and 2.1 percent of the carbamate burned but at a much slowerrate than polystyrene. All of the above copolymers have equivalent orbetter physical characteristics than polystyrene does.

EXAMPLE 2 EXAMPLE 3 2,3-Dibromopropyl-N-vinyl carbamate is prepared byreacting equimolar amounts of 2,3-dibrornopropyl alcohol with vinylisocyanate in chloroform by the procedure employed in Example 1. A whitesolid is obtained by recrystallization from n-hexane which has a meltingpoint of 6768.5 C and elemental analysis as follows:

Found Calculated C 25.5 25.1 H 3.3 3.14 N 5.0 4.85 Br 54.65 55.47

Spectral analysis confirms the dibromopropyl-N-vinyl carbamate.

A copolymer of this carbamate with styrene is prepared by thepolymerization procedure of Example 1. The resulting copolymer isanalyzed and found to contain ==l percent of the carbamate. Test bars (6X k X 36 inch) of the copolymer are found to be fire retardant.

structure of 2,3-

EXAMPLE 4 In a manner similar to the polymerization procedure describedin Example 1, 2,3,4,5,6-pentabromo-N-vinyl carbamate is polymerized andrecovered as a solid, thermoplastic material capable of being moldedinto a variety of shapes. Test bars (6 X A X 7% inch) of the polymerpass both UL-94 and ASTM D-635 tests for fire resistance properties.

EXAMPLE 5 In a manner similar to the polymerization procedure describedin Example 1, a monomeric mixture of 10 parts of2,3,3-tribromoallyl-N-vinyl carbamate, 70 parts of styrene and 10 partsof methyl methacrylate is polymerized and recovered as a solid,thermoplastic material capable of being molded into a variety of shapes.Test bars (6 X lie X 1% inch) of the polymer pass both UL-94 and ASTMD-635 tests for fire resistance.

EXAMPLE 6 In a manner similar to Example 4, a mixture of 15 parts ofbis(vinyl carbamate) corresponding to the formula:

and parts of styrene is polymerized, recovered and found to be fireresistant in accordance with UL-94 and ASTM 13-635. The resultingcopolymer is a therrnoset resin.

What is claimed is:

1. A polymer of a halogenated carbyl-N-alkenyl carbamate represented bythe formula:

A[ O ENE-Y1 Mal wherein R, and R are individually hydrogen or alkylhaving from one to six carbon atoms; R R and R: are individuallyhydrogen, alkyl or alkenyl having from one to eight carbon atoms, arylhaving from six to 16 carbon atoms, haloalkyl or haloalkenyl having fromone to eight carbon atoms and from one to eight halogen atoms, orhaloaryl having from six to 16 carbon atoms provided at least one of Rand R contains halogen and b is zero or a whole number from 1 to 6, saidpolymer being formed by free radical catalysis.

3. The polymer according to claim 2 wherein the carbamate has at leastone halogen atom per four carbon atoms.

4. The polymer according to claim 2 wherein the carbamate is representedby the formula:

wherein R, is alkyl having one to three carbon atoms, X is halogen; b isO or 1; c, d, and e are individually 0, l, 2, or 3.

5. The polymer according to claim 4 wherein the carbamate istribromoneopentyl-N-vinyl carbamate.

6. The polymer according to claim 4 wherein the carbamate is2,3-dibromopropyl-N-vinyl carbamate.

7. The polymer according to claim 1 wherein the carbamate is representedby the formula:

wherein R is hydrogen or alkyl having 1 to 6 carbon atoms; Z is hydrogenor halogen; X is halogen; b is 0, I, 2 or 3; and c is 1, 2,3, or 4.

10. The polymer according to claim 9 wherein the carbamate is2,3,3-tribromoallyl-N-vinyl carbamate.

11. The polymer according to claim 1 wherein the carbamate isrepresented by the formula:

wherein R, and R are individually hydrogen or alkyl having from one toeight carbon atoms; R and R are individually hydrogen, alkyl having fromone to six'carbon atoms, alkenyl having from two to eight carbon atoms,aryl having from six to 16 carbon atoms, haloalkyl having from one toeight carbon atoms, haloalkenyl having from two to eight carbon atoms,or haloaryl having from six to 16 carbon atoms with the proviso that atleast one of R and R contains halogen; b is 0 or a whole number from 1to 6 and f is a whole number from I to 6.

12. The polymer according to claim 1 wherein the carbamate, as definedin claim 1 is copolymerized with an ethylenically unsaturated monomer.

13. The polymer according to claim 12 wherein the ethylenicallyunsaturated monomer is styrene.

14. A self-extinguishing copolymer according to claim 13 wherein fromabout 3 to about 50 weight percent of tribromoneopentyl-N-vinylcarbamate is copolymerized with from about 97 to about 50 weight percentof styrene.

2. The polymer according to claim 1 wherein the carbamate is representedby the formula: wherein R1 and R2 are individually hydrogen or alkylhaving from one to six carbon atoms; R3, R4 and R5 are individuallyhydrogen, alkyl or alkenyl having from one to eight carbon atoms, arylhaving from six to 16 carbon atoms, haloalkyl or haloalkenyl having fromone to eight carbon atoms and from one to eight halogen atoms, orhaloaryl having from six to 16 carbon atoms provided at least one of R3and R5 contains halogen and b is zero or a whole number from 1 to 6,said polymer being formed by free radical catalysis.
 3. The polymeraccording to claim 2 wherein the carbamate has at least one halogen atomper four carbon atoms.
 4. The polymer according to claim 2 wherein thecarbamate is represented by the formula: wherein R1 is alkyl having oneto three carbon atoms, X is halogen; b is 0 or 1; c, d, and e areindividually 0, 1, 2, or
 3. 5. The polymer according to claim 4 whereinthe carbamate is tribromoneopentyl-N-vinyl carbamate.
 6. The polymeraccording to claim 4 wherein the carbamate is 2, 3-dibromopropyl-N-vinylcarbamate.
 7. The polymer according to claim 1 wherein the carbamate isrepresented by the formula: wherein R1 is hydrogen or alkyl having fromone to six carbon atoms; R is halogen or haloalkyl; b is 0, 1, 2 or 3; eis 0, 1, 2, 3 or 4; and g is 1-5.
 8. The polymer according to claim 7wherein the carbamate is 2, 3,4,5,6-pentabromophenyl-N-vinyl carbamate.9. The polymer according to claim 1 wherein the carbamate is representedby the formula: wherein R1 is hydrogen or alkyl having 1 to 6 carbonatoms; Z is hydrogen or halogen; X is halogen; b is 0, 1, 2 or 3; and cis 1, 2, 3, or
 4. 10. The polymer according to claim 9 wherein thecarbamate is 2, 3,3-tribromoallyl-N-vinyl carbamate.
 11. The polymeraccording to claim 1 wherein the carbamate is represented by theformula: wherein R1 and R2 are individually hydrogen or alkyl havingfrom one to eight carbon atoms; R3 and R5 are individually hydrogen,alkyl having from one to six carbon atoms, alkenyl having from two toeight carbon atoms, aryl having from six to 16 carbon atoms, haloalkylhaving from one to eight carbon atoms, haloalkenyl having from two toeight carbon atoms, or haloaryl having from six to 16 carbon atoms withthe proviso thAt at least one of R3 and R5 contains halogen; b is 0 or awhole number from 1 to 6 and f is a whole number from 1 to
 6. 12. Thepolymer according to claim 1 wherein the carbamate, as defined in claim1, is copolymerized with an ethylenically unsaturated monomer.
 13. Thepolymer according to claim 12 wherein the ethylenically unsaturatedmonomer is styrene.
 14. A self-extinguishing copolymer according toclaim 13 wherein from about 3 to about 50 weight percent oftribromoneopentyl-N-vinyl carbamate is copolymerized with from about 97to about 50 weight percent of styrene.